Soft gelatin capsules comprising principally gelatin, glycerol and water are used for the administration of solids, masses and liquids. They are desirable dosage forms for the administration of many therapeutic substances such as drugs having a bitter taste or are in liquid form. In addition, the gelatin shell wall being readily soluble in the stomach, the contents are more readily absorbed due to the absence of excipients usually present in other oral dosage forms such as tablets and pills. Soft gelatin capsules are particularly suitable for dispensing liquids such as fixed and volatile oils.
The preparation of soft gelatin capsules is described, for example, in Lachman, Theory and Practice of Industrial Pharmacy, Lea & Febiger, Philadlephia, Second Edition, 1986.
U.S. Pat. No. 4,804,542 discloses a soft gelatin capsule consisting of a capsule sheath and a capsule filling wherein the capsule sheath consisting of gelatin and a small amount additive in the sheath such as starch, starch derivative, cellulose, cellulose derivative, milk product and so on.
In the usual practice, the empty soft gelatin capsule is filled with the desired material. Thereafter, the empty gelatin capsule is sealed.